Amino and other functional groups were introduced to a polyethylene substrate starting from the unsaturated pendant and bridge
groups (collectively called side chains) of polyethylene, which had been prepared by γ-ray irradiation under an atmosphere
of 1,3-butadiene of the polyethylene substrate (the drawn film of ultra-high- molecular-weight polyethylene, Mˉv: 5 × 106). 2-Aminoethylamino groups were introduced to the side chains through treatment either with bromine or with peracetic acid
vapor followed by immersion in ethylenediamine. Introduction of amino groups were confirmed by Fourier transform IR spectrometry,
ninhydrin test, and acid–base titration. Starting from 2-aminoethylaminated polyethylene, modification cycles to grow a dendrimer
on the film were applied; these consisted of 2-methoxycarbonylethylation and 2-aminoethylamidation. This technique resulted
in hyperbranched modification of the polymer. The product is a kind of dendrimer grown on the surface of polyethylene film
with amplified amino ends and has anion-exchange capacity and absorbs acid dye. Its application in practical uses is discussed.
Received: 31 March 2000 Accepted: 2 January 2001 相似文献
During the 1950s to the end of the 1970s the United States Army developed the basic methodology to produce shelf-stable irradiated meat, seafood and poultry products. These products are normally packed without gravy, sauce or brine, as liquid is not required to sterilize the product as in the canning process. This leads to the distinctive “dried cooked” taste normally associated with roasts opposed to the casserole taste usually associated with tinned meats. The Biogam group at the Atomic Energy Corporation of South Africa is currently producing shelf-stable irradiated meats on a commercial basis. The meats are cooked, chilled, portioned, vacuum packed and irradiated to the required minimum dose of 45 kGy at a temperature of between −20 and −40°C to ensure absolute sterility even under tropical conditions. The product is packaged in a high quality four layer laminate pouch and will therefore not rust or burst even under adverse weather conditions and can be guaranteed for more than two years as long as the integrity of the packaging is maintained. Safari operators in remote parts of Africa, mountaineers, yachtsmen, canoeists and geological survey teams currently use shelf-stable irradiated meat products produced in South Africa. 相似文献
Gamma-irradiation was found to affect the physicochemical properties of dry red kidney beans. The highest dose used (8 kGy) significantly (P0.05) modified the extent of deamidation, the number of sulfhydryl groups, as well as the solubility and the hydrophobicity of the protein. Deamidation, protein solubility and hydrophobicity all increased with the irradiation dose while the number of sulfhydryl groups was reduced by the treatment. Furthermore, irradiation also affected the outgrowth of natural filamentous fungi contaminants present on the dry beans. A dose of 1.5 kGy reduced the number of filamentous fungi by 2 log cycles immediately after treatment. However, the highest dose used (3 kGy) did not eliminate the filamentous fungi completely. Moreover, the filamentous fungi population was a lot less diversified on the irradiated samples. Species of Aspergillus sp. and Penicillium sp. were more abundant on the unirradiated beans while the beans irradiated at 3 kGy contained were predominantly infected by species of Rhizopus sp. , Cladosporium sp. and Alternaria sp. 相似文献
Degree of microbiological decontamination, organoleptic and physico-chemical properties of natural honeys were investigated after radiation treatment. Seven kinds of honeys were irradiated with the beams of 10 MeV electrons from a 10 kW linear accelerator “Elektronika 10-10” at the dose 10 kGy.
It was shown, that after irradiation, the total count of aerobic and anaerobic bacteria and moulds decrease by 99%. The antibiotic value in investigated honeys increased in turn from 1.67 to 2.67 after irradiation. Such factors and parameters of investigated honeys as their consistency, content of water and saccharose, acidity, the diastase and 5-HMF values were not changed significantly after irradiation.
Decontamination by irradiation is a process which allows us to obtain high microbiological purity of honeys. It is especially needed, when honeys are used in surgical treatment of injuries and in nutrition of babies with food deficiency. 相似文献
In the Institute of Nuclear Chemistry and Technology research on microbiological decontamination of medicinal herbs by irradiation has been carried out since 1996. It was shown that using ionizing radiation (a dose of 10 kGy) can obtain satisfactory results of microbiological decontamination of these products. The content of essential biologically active substances such as essential oils, flavonoids, glycosides, anthocyans, antra-compounds, poliphenoloacids, triterpene saponins, oleanosides and plants mucus did not change significantly after irradiation. Pharmacological activity of medicinal herbs has been found satisfactory after microbiological decontamination by irradiation. 相似文献
The hygienic, physicochemical, and organoleptic qualities of white ginseng were monitored during 6 months under accelerated conditions (40°C, 90% r.h.) by observing its microbial populations, disinfestation, and some quality attributes following either gamma irradiation at 2.5–10 kGy or commercial phosphine (PH3) fumigation. In a comparative study, both treatments were found to be effective for disinfecting the stored samples. Phosphine showed no appreciable decontaminating effects on microorganisms contaminated including coliforms, while 5 kGy irradiation was sufficient to control all microorganisms related to the quality of the packed samples. Irradiation at 5 kGy caused negligible changes in physicochemical attributes of the samples, such as ginsenosides, amino acids, fatty acids, and organoleptic properties, whereas phosphine fumigation was found detrimental to sensory flavor (P<0.01). Quality deterioration occurred in the commercially-packed samples was in the following order: the control, 10 kGy-, phosphine-, and 2.5–5 kGy-treated samples. Accordingly, irradiation at <5 kGy was found to be an effective alternative to phosphine fumigation for white ginseng. 相似文献